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# gfdl's home page > people > keith dixon > arctic sea ice changes in gfdl r30 experiments

arctic sea ice changes in gfdl r30 experiments

[CM2.1 sea ice icon] On this page, we show some results from sets of coupled climate model experiments conducted at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey. This page shows results from an older climate model is known as the GFDL R30 coupled model. The new climate model used is known as the GFDL CM2.1 climate model. The GFDL R30 coupled model used to conduct the simulations was representative of the state-of-the-art in global climate modeling in the 1990s. A newer and more sophisticated model has been developed at GFDL. Named CM2.1, this new model has served as GFDL's workhorse model for these type of studies starting in 2004. You may follow this link to view CM2.1 sea ice model results].

Though there are uncertainties associated with both the 21st century projections of greenhouse gas and sulfate aerosol levels and the coupled general circulation models themselves, these GFDL model results suggest that the Arctic is a region where one can look for climate change signals.

Not all of the figures presented here have been published in the peer-reviewed literature. (However, all of the model experiments from which the figures were derived have been documented in peer-reviewed scientific journals.) We request that if you have any questions, please contact us before you copy or cite the figures on this web page.

Older R30 model results

In the R30 model simulations the effective levels of greenhouse gases and tropospheric sulfate aerosols are varied in time according to historical reconstructions and IPCC projection scenario IS92a. The experiments simulate the period extending from the mid-1800s through the middle of the 21st century. The various components of the global coupled model (e.g., the atmosphere, ocean, land surface, and sea ice) respond to the prescribed changes in greenhouse gases and aerosols. One notable feature of these greenhouse scenario simulations is that the amount of Northern Hemisphere sea ice begins to decrease markedly as one approaches the year 2000. Compared to the control experiment (i.e., a companion experiment that experiences no changes in greenhouse gases or aerosols), the suite of greenhouse scenario experiments simulate the loss of roughly half of the volume of sea ice found north of 67 degrees North latitude, by the year 2050.

Although there are uncertainties associated with both the R30 coupled general circulation model and the IS92a projection of greenhouse gas and sulfate aerosol levels, these preliminary GFDL model results suggest that the Arctic may be a region in which one can look for climate change signals. Three sets of images are presented here to summarize these model results.

REFERENCE: Dixon, K. W., T. L. Delworth, T. R. Knutson, M. J. Spelman, and R. J. Stouffer, 2003: A comparison of climate change simulations produced by two GFDL coupled climate models. Global & Planetary Change, 37(1-2), 81-102.
[ABSTRACT] [PDF paper]

For additional information about these GFDL R30 coupled air-sea model results, please contact either Keith Dixon (email: Keith.Dixon @ noaa.gov ; phone: 609-452-6574) or Tom Delworth (email: Tom.Delworth @ noaa.gov).

GFDL R30 model results on this page	maps & movies of GFDL R30 simulated arctic sea ice changes	graph of GFDL R30 simulated arctic sea ice volume changes
GFDL R30 model results on this page	graph depicting the polar amplification of the greenhouse warming signal in the GFDL R30 model	links to some related materials & background info

maps & movies of simulated arctic sea ice changes The two figures and related animations listed below summarize the time evolution of sea ice thicknesses simulated in GFDL's R30 atmosphere-ocean general circulation model climate change experiments. The uppermost figure shows how the model-simulated total volume of Arctic sea ice (i.e., sea ice poleward of 67N) decreased by about 20% over the 50-year period extending from the 1950s to the first decade of the 21st century. The lower panel depicts how the simulated loss of Arctic sea ice continued so that almost one-half of the model's Arctic sea ice volume has been lost at the end of the 100-year period from the 1950s to the 2050s. (The white bar graphs at the bottom of the figures represent the total volume of Arctic sea ice projected for the different time periods).
	click here for a TIFF version of the 1950s vs 2000s panel [291KB] click here for a TIFF version of the 1950s vs 2050s panel [291KB]
	click here for a INDEO5.AVI animation of the 100 year time series [5.6MB] click here for a MJPEG.MOV animation of the 100 year time series [14.7MB] click here for a MJPEG.AVI animation of the 100 year time series figure [14.7MB]

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graph of simulated arctic sea ice volume changes

The figure below shows how the total volume of sea ice located north of 67 degrees North latitude varies over time in coupled atmosphere-ocean climate model experiments performed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The graphed numbers represent the average of three climate change scenario experiments performed using the GFDL R30 coupled model climate. Averaging the results of three experiments yields a smoother curve, making it easier to see the greenhouse gas-induced signal among the year-to-year noise of interannual variability.
The Y-axis is in units of percent, with 100 percent representing the average Arctic sea ice volume simulated in the three model experiments for the decade 1950 to 1959. So, by the year 2000, the total volume of Arctic sea ice present in the model is between 75 and 80 percent of that which was simulated to exist in the 1950's. In these coupled climate model simulations, the total volume of Arctic sea ice continues to decrease during the 21st century, so that only about half of that which was present in the 1950s is projected to remain in the year 2050.

You may download a [ TIF Version ] of this figure.
You may download a [ Postscript Version ] of this figure.

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graph depicting the polar amplification of the greenhouse warming signal

The figure below depicts how the simulated surface air temperatures change when averaged over the same three GFDL R30 coupled model climate change scenario experiments discussed above. (Note that the Y-axis is in degrees Fahrenheit, and the temperature changes are referenced to the same 1950 to 1959 base period used in the above sea ice graph.)
The red shaded area shows the simulated temperature rise that occurs over the Arctic (an average from the Arctic Circle northward to the North Pole), where temperatures are projected to be between 7 and 8 degrees Fahrenheit warmer in 2050 than in the 1950s. The black circles show the changes in the Global Average Surface Air Temperature for the same time period. In response to increasing levels of atmospheric greenhouse gases, the modeled global mean surface air temperature warms by between 3 and 4 degrees Fahrenheit by 2050 as compared to the 1950s.

You may download a [ TIF Version ] of this figure.
You may download a [ Postscript Version ] of this figure.

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links to some related materials & background info

Note: The United States Government does not endorse any of the non-Federal websites that may be listed on this page.
When you click on any of the links presented below, you may be leaving the GFDL website.

For more information about the GFDL R30 model experiments from which the figures on this page were derived, see

Dixon, K. W., T. L. Delworth, T. R. Knutson, M. J. Spelman, and R. J. Stouffer, 2003: A comparison of climate change simulations produced by two GFDL coupled climate models. Global & Planetary Change, 37(1-2), 81-102.
[ABSTRACT] [PDF paper]

artic sea ice trends: observations & model results

See Thinning of the Arctic Sea-Ice Cover, by D.A. Rothrock, Y. Yu, and G.A. Maykut, Geophysical Research Letters, Vol. 26, No. 23, pp 3469-3472, Dec. 1, 1999.
Also available in PDF form.
Additional information realted to this GRL article can be found at the Rothrock et al. Web Page at U. Washington's Polar Science Center.
The arctic ice thickness anomaly of the 1990s: A consistent view from observations and models, by DA Rothrock, J. Zhang, and Y. Yu appeared in the Journal of Geophysical Research, 108(C3), 3083, doi: 10.1029/2001JC001208, 2003.
The paper A Mechanism for the High Rate of Sea-ice Thinning in the Arctic by Cecilia Bitz and G. H. Roe describe how thermodynamic effects and related feedbacks (and not wind changes) could be associated with rapid sea ice thinning, especially in areas where the ice was relatively thin to begin with.
To read an opinion that the submarine locations available to Rothrock et al may have been biased toward locations where the ice thinning was more dramatic due to wind effects, see the web page Is Arctic sea ice rapidly vanishing? (Greg Holloway and Tessa Sou, Institute of Ocean Sciences, Sidney, British Columbia.) Later published as Has Arctic Sea Ice Rapidly Thinned?, Holloway, G., and Sou, T., Journal of Climate [J. Clim.]. Vol. 15, no. 13, pp. 1691-1701. Jul 2002.
In the 30 August 2002 issue of Science Richard A. Kerr wrote a news piece entitled Whither Arctic Ice? Less of It, for Sure [PDF] that sought to summarize the current level of understanding understanding regarding 20th and 21st century Arctic sea ice changes. A version of the figure seen near the top of this web page was used to illustrate the article.
Also see Arctic Sea Ice Thickness Remained Constant During the 1990s by P. Winsor, Geophysical Research Letters, Vol. 28, No. 6, pp 1039-1041, March 15, 2001.
Also in PDF form.
Results of GFDL's older R15 coupled model were included in Global Warming and Northern Hemisphere Sea Ice Extent, a paper that appeared in the 3 December 1999 issue of Science by K. Y. Vinnikov, A. Robock, R. J. Stouffer, J. E. Walsh, C. L. Parkinson, D. J. Cavalieri, J. F. B. Mitchell, D. Garrett, and V. F. Zakharov, (pp. 1934-1937). Click here or on the small figure to the right, to see a full sized graph from the Vinnikov et al paper comparing sea ice trends in the GFDL R15 model, a Hadley Centre model, and observations.
[on line abstract].
Thinning of the Arctic sea-ice Graphic from the United Nations Environment Programme, GRID-Arendal.
New York Times science writer William K. Stevens also discussed sea ice trends simulated in the GFDL model in his 7 Dec. 1999 article, Arctic Thawing May Jolt Sea's Climate Belt.
The GFDL R30 coupled model used to conduct the simulations was representative of the state-of-the-art in global climate modeling in the 1990s. A newer and more sophisticated model has been developed at GFDL. Named CM2, this new family of models has served as GFDL's workhorse models for these type of studies starting in the spring of 2004. [You may view the CM2.1 Sea Ice Model Results].
The older R30 coupled model runs depicted on this page used a relatively unsophisticated sea ice model. Its lineage can be traced back to the relatively simple model developed by Kirk Bryan in 1969, though several updates have been made since that time. At each gridpoint, average sea ice thickness is predicted, but not fractional coverage (i.e., the grid cell is either considered ice free or entirely covered by ice of some thickness). The ice moves freely with the surface ocean currents, provided the thickness is less than 4 meters, at which point additional convergence of sea ice is not permitted. Wind stresses computed by the atmospheric model component are passed directly to the liquid ocean general circulation model below, without any modification by the sea ice. Fluxes involving the latent heat of fusion are conserved through the coupled model system during freezing and melting. Similarly, brine rejection and surface water freshening occur in a conservative manner as the sea ice forms or melts. The albedo is dependent on the thickness and surface air temperature. The model instantly converts into sea ice any snow that falls upon pre-existing sea ice.